From August 3-7, researchers from Colombia’s Unidad de Busqueda para Personas dadas por Desaparecidas (the Missing Persons Search Unit, or UBPD), The Ohio State University, and Principal Investigator Dr. Mattieu Baudelet of Central Florida University conducted exploratory research in Medellin, Colombia. Facilitated by Ohio State’s Mershon Search Lab, Professor Baudelet, Ohio State Professor Nick Passalacqua, Ohio State Anthropology PhD student Jazmin Borrayo, and Mershon Search Lab Co-Director Derek Congram worked with UBPD staff to collect data as part of a pilot study to establish the utility of Laser-induced Breakdown Spectroscopy (LIBS) for differentiating commingled (mixed) skeletal remains.

The goal of the research is to help establish a new method for forensic investigation that can individualize the bones of people whose remains are found commingled; individualization would support their analysis and identification so that they can be returned to families for dignified burial. To date only preliminary studies on small samples or highly degraded remains, or larger studies with archaeological remains have been tested with LIBS. The cases in the custody and care of the UBPD laboratory in Medellin provide an excellent opportunity to collect data using LIBS from bones to establish the range of variability of chemical elements amongst individualized skeletons of forensic interest, as well as to determine the range of differences of elements among bones from different individuals.

Commingling is a problem faced by many countries around the world, including Bosnia-Herzegovina and Syria. The UBPD has to work on commingled remains particularly when the dead in cemeteries have been placed in communal ossuaries. Investigations have shown that possible conflict victims have been buried in communal ossuaries with other deceased persons, whose deaths were not relate to the armed conflict. Being able to isolate conflict victims from others can save significant time as well as human and material resources - particularly with respect to DNA analysis, which is relatively expensive and time-consuming. If LIBS is demonstrated to be able to adequately differentiate individuals, it will also serve in other contexts of armed conflict and disasters.

LIBS works by emitting a laser from a hand-held spectrometer (“analyzer”) onto a surface material such as bone. The analyzer then measures the chemical element profile of the material. After the levels and spectra of elements are recorded, statistical tests can be used to establish the ranges of variation between different bones of the same individual and the likelihood that bones are from different people. Ideally, this method would be used in association with traditional methods of sorting mixed remains, including anthropological sorting by pair matching and by taking into consideration contextual information about where the bones were recovered. In instances where doubt remains, limited DNA testing can validate the sorting that has been done by LIBS and anthropology.

Over the course of five days, the researchers collected 948 profiles from different bodies. Once statistical analysis of the ranges of these profiles is complete, the level of difference between individuals can be established, which will determine how useful LIBS is as a method for individualizing bodies. Should this be successful, follow-up training can be conducted to ensure further data collection and implementation of the method.

The UBPD, tasked with leading the inter-institutional investigation of people missing due to decades of armed conflict in Colombia, has hundreds of staff working every day to resolve more than 137,000 disappearances. An investment of their limited resources in research – that is never guaranteed to be successful – is perceived by many as gratuitous. The Mershon Search Lab mobilizes researchers and ideas to complement the work of the UBPD, to take on this task with the hope of helping bring answers to families both in Colombia and around the world.